Communication system



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Jun@ 9 WM, H. c. CURL V COMMUNICATION SYSTEM Filed March 50, 1932 3 Sheets-Sheet l ATTRNEV June v.3; H. c. CURL COMMUNI CATION SYSTEM Filed March 30, 1932 3 Sheets-Sheet 2.

FIG. 2

INVENTOR H C. CURL BY ATTORNEY June 9, 193. H. c. CURL COMMUNICATION SYSTEM Filed March 30, 1952 5 Sheets-Sheet 3 /N VENT OR H. c. cum

ATTORNEY Patented June 9, 1936 UNITED STATES Ahhi'i FFIQE Telephone Laboratories,

Incorporated, New

York, N. Y., a corporation of New York Application March 30,

8 Claims.

This invention relates to communication systems and the object of the invention is to improve and correlate several such systems so as to obtain a desired priority between the transmitting stations of the several systems for the various purposes for which they may be used.

Announcing systems have been proposed heretofore in which a number of groups of receivers are energized from a single amplifying system with which a number of transmitting stations are associated, each having selecting switches for connecting the desired receiver groups and means for locking out other transmitting stations to avoid interruptions while messages are being transmitted.

In some applications, such as naval ships for example, it has been found desirable to provide several such systems which normally function independently of each other. According to the present invention, the transmitting stations of one of these systems are equipped to transmit either telephone messages orcode signals for alarm purposes and, for general announcing purposes, means is provided at such stations for connecting to the system the receiversof the other systems if they are not already in use. For alarm purposes such stations may obtain control of all the receivers of the several systems whether or not they are already in use.

An important feature of the invention is means at each station which may be operated to permit a station locked out by another station using the system, to assume control of the system when the circumstances warrant such action. If another station operates its corresponding mechanism, such other station is operatively connected but cannot disable the first station as it would under normal operating conditions.

These and other features of the invention will be more clearly understood from the following detail description and the accompanying drawings in which Figs. 1, 2 and 3 considered together show a complete system according to the invention.

The system shown by way of illustration comprises two normally independent but interconnected systems one of which is shown on Figs. 1 and 2 and the other on Fig. 3. The first system comprises three transmitting stations ll, l2 and I3, amplifiers l4 and I5 and several groups of loud speaking receivers I6, ll, 18 and [9. Each station, as shown in detail for station II is equipped with a telephone transmitting set 20,

an alarm signal set 2i, a portable transmitter 22 worn by the operator and a cut-in switch 23 for 1932, Serial No. 602,091

obtaining control of the system when it is already in use by another station. Since stations l2 and i3 are identical with station ll, similar connections are omitted in order to simplify the drawings.

The system of Figs. 1 and 2 is put in condition for operation by first closing either the master switch 2d of the set 2t! or the master switch 25 of the signal set 2i according to whether speech or code signals are to be transmitted. Relay 26 (Fig. 2) is thereby operated by current from the positive of the direct current source i traversing a circuit including conductor 2?, the relay winding, conductors 28, 29 and til, contact E8! of the master switch 2 conductors 3!, 32 and conductor 33 leading to the negative terminal of the generator or other source of supply ii.

If the master switch 25 is operated instead of switch 24 the circuit for relay 26 is completed by the current in conductor 29 traversing contact 34 of switch 25 and conductor 32 to negative as before. If speech is to be transmitted by means of the portable transmitter the circuit for this relay is made by contact 35 of the jack 35 when the transmitter plug .il is inserted.

The operation of relay 26 closes contact 38 to make current available for operating the other relays and operates relay 39 which connects alternating current from the source 40 directly to the power supply unit of the amplifiers l4 and I5. It will be observed that before the operation of this relay the current flows to the amplifiers by way of conductors i2, 43 and resistance 46 which is sufficient to keep the amplifier tube filaments just below the emission temperature. The operation of the relay 39, however, closes contact 45 which shunts out the resistance so that the filaments are quickly raised to operating temperature. The closing of contact it completes the circuit for the rectifier of amplifier it over conductor 41 so that plate voltage is made available for amplifier Hi and for amplifier l5 by means of conductor 2l3. This arrangement avoids delay in starting by making it unnecessary to wait for the tubes to become heated.

Priority relays 48, iii and 5e are provided, one for each of the transmitting stations of Fig. 1 and the first station to operate its relay gets exclusive control of the system. For example at station ll relay 43 is operated by the closing of contact 5| of switch 24 or contact 52 of jack 36, the circuit extending from negative conductor 33, contact 38, of relay 2%, conductors 53 and 54 to conductor 55, then to either contact 5! or 52, conductor 56, the winding of relay 48, contact 51 of relay 49, contact 58 of relay 59 to conductors 59, 69, contact SI of relay 26 and conductor 21 to positive.

The operation of relay 48 opens contact 62 in the operating circuit of relay 49 and contact 63 in the operating circuit of relay 59 so that neither station I2 nor I3 can now obtain control of the system in the normal manner. Relay 48 also closes contact 64 to complete a circuit for relay 95 extending from positive conductor 59, contact 64, winding of relay 65, conductor 65 to negative conductor 55. Relay 65 opens contact Bl in the circuit of local receiver 58 so that singing due to acoustic coupling between the local transmitter and the local receiver is prevented. If preferred, a resistance of suitable value may be connected across contact 51 so that the breaking of the contact merely reduces the volume level at which the local receiver can operate. Relay 55 also closes contacts 69, ID in the talking circuit of transmitters 22 and II and contacts I2, 73, I4, I5 and I6 which prepare operating circuits for receiver group selecting magnets I1, 18, I9, 80 and 8I (Fig. 2). The operator then closes one or more of the locking keys 82 to 86 according ot the number of receiver groups to be energized. The corresponding relays are then operated over a circuit extending from negative conductor 55, conductors 8?, 88, through the operated keys, contacts E2 to IE5 of relay 65, conductors 89 to 93, conductors 94 to 98, through the relays 'I? to BI to conductor 99 and positive conductor 69.

The operation of these relays completes the talking circuit which is as follows: from transmitter 22 or lI, conductors I99, IIlI, contacts 59, 19, conductors I92, I93 to the input of amplifier I5 from the output of this amplifier to the input of power amplifier I4 by conductors I94, I95, from the output of amplifier I4 by conductors I96, I81, through contacts I88, I99 of relay H9 ceiver groups.

(previously operated by the operation of relay 25) to conductors III, II2, associated with the armatures of relays TI to 8I and from the armatures of these relays to the respective receiver groups I6, I], I8 and I9 and group II3 of the system of Fig. 3, when relay H4 is not operated as explained below.

Messages may then be spoken into either transmitter for reproduction by all the selected re- In order to prevent variations in loading on the amplifier system in accordance with the number of receivers being energized,each group relay has associated therewith a resistance, such as I24 of relay H, which simulates the impedance of the corresponding receiver group and is connected across the amplifier output conductors I I I and I I2 whenever the relay is not operated. It will be noted that transmitter 'II is operatively connected into the talking circuit by contacts H5, H6 of the master switch 24 and that the insertion of plug 31 into jack 35 shunts the talking circuit by a resistance II? which is disconnected only when transmitter 22 is actually in use by operating hand switch II8 associated with the transmitter. This resistance prevents the introduction of unnecessary noise into the receiver circuits while the operator is not actually speaking.

Each telephone set 20 is provided with signal lamps H9 and I20. Lamps II9 are lighted whenever relay 25 is operated, that is whenever any one of the stations of that system'is using the system either for speech or alarm signals. Lamps I29 are lighted by the operation of relay I2I of the system of Fig. 3, that is to say these lamps give an indication at stations II, I2 and I3 whenever either of the stations I22 and I23 of the other system is using loud speaker group H3. In such case, relay II4 (Fig. 3) will be operated so that 5 the operation of key 85 in telephone set 29 is not effective to place receiver group [I3 under the control of station II.

If an operator at station I2 or I3 desires to use the system and, ignoring the warning of his 10 lamp II9 that the system is already in use, operates his master switch or plugs in his portable transmitter, he cannot in this way obtain control of the system since as already pointed out the operating circuits of priority relays 49 and 59 have been opened by the operation of priority relays 48. However, if any station has some urgent message to transmit while the system is already in use, the operator may operate both his master switch and his cut-in switch. At station II, for example, the operation of cut-in switch 23 closes a circuit for cut-in relay I25 extending from positive conductor 59 through the relay, conductor I26, contact I2! on master switch 24, conductor I28, cut-in switch 23, con- 2 ductor 87 to negative conductor 55. The operation of relay I25 operates priority relay 48 over a circuit extending from positive conductor 59, armature of relay l25, conductor I29, winding of relay 49, conductor 56, contact 5|, conductor I39 to negative conductor 55. If instead of operating the master switch the portable transmitter is plugged in, the circuit of relay 48 is completed from conductor 55 by conductor I3I, contact 52 of jack to negative conductor 55. As before the operation of relay 48 gives control of the system to station I I and disables stations I2 and I3 by opening the circuits of relays 49 and 58.

If the operator neglects to reopen his cut-in switch which is of the locking type, when he has finished his message, relay 48 is nevertheless released by the opening of contact 52, when transmitter plug 37 is removed, or by the opening of contact 5I on master switch 24 which returns to the unoperated position automatically when it is no longer held closed. Any other station may then use the system in the normal way. However, if a second station has an emergency message to transmit while station II is 50 already operating by means of its cut-in key, the second operator may close his cut-in key to operate his priority relay so that his transmitter is also connected with the system in a manner similar to that already described with reference to station II.

If under any of the operating conditions already described a station desires to send code signals over the system, the operator closes his alarm signal switch 25. The closure of contact 34 energizes the system as already described and contact I33 closes a circuit from negative conductor 88 through the contact to conductor I34, relay I35 (Fig. 2) and conductor I36 to positive through contact 6| of relay 25. The operation of relay 35 completes the operating circuits of 7 all group receiver relays TI to BI from positive conductor 69 to negative conductor 55 through contacts I31 to I4I, and the circuits of local receivers 58, I42 and I43 through contacts I44,

M5 and I45, respectively.

When the system of Fig. 3 is not, being used by either of the stations I22 or I23, relays I41 and I43 are unoperated so that local receivers I49, I59 are connected across conductors I5I, I52

of loud speaker group II3 through the back contacts of the relays' Relay H4 will also be unoperated so that the operation of relay 18 (Fig. 2) connects group M3 to the output of amplifier It by means of conductors I53, E54 and back contacts I55, I56 of relay II l. If the system of Fig. 3 is being used, relay I2! (which corresponds to relay 26 in the other system) will be operated and current will flow from positive terminal of source I51 through contact I58 of the relay, conductors l59, Hit, relay IGI, conductor I62, contact I63 on master switch 25 (Fig. 1), conductors I54, I65 to negative terminal of source I51 through contact E66 on relay MI. The operation of relay I6! releases relay H4 by opening contact Hill to associate receiver group H3 with relay l8 of Fig. 2, thereby placing it under the control of alarm signal set El (Fig. 1). Relay ltl also closes contacts I69, llt which connect local receivers I ie, Hit to conductor l5i irrespective of the position of relays Ml and I48, by means of conductors ill, H2 and H3. Hence it is seen that the operation of switch 25 is effective to connect all receivers of both systems to amplifiers I 4 and I5.

Contact of master switch 25 which operated relay E35 also completes a circuit over conductor il for relay H5 in the amplifier l5. This relay converts the amplifier into an oscillator for signal purposes in the well known manner as described for example in Patent 1,571,357 to Whiting et al., February 2, 1926. The system is now in condi tion for transmitting code signals and. the operation of key H6 in the set 2i alternately operates and releases relay ill in the amplifier I5 to cause the amplifier to function as an oscillator intermittently and energize the receivers according to the code signals transmitted. Upon the completion of the message, key H6 and master switch 25 are released and all relays previously operated including the power supply relay 25 are thereby released so that the system may be reenergized by any other station desiring to transmit a message.

The system of Fig. 3 has already been partially described in connection with the operation or" the stations of Fig. 1. This system is in general similar to that of Figs. 1 and 2 except that no portable transmitter, alarm signal stations or receiver group selecting circuits are provided. While the system as shown is effective in illustrating how two or more systems may be interconnected for emergency purposes, it will be understood that one or more of the above features may be added to the additional systems if desired.

The operation of master switch N8 of telephone set l'lil at station I22 closes contact I to complete a circuit for relay WI. The operation of this relay connects conductor I59 to the positive terminal of source l5? to make current available for the operation of the rest of the system. The closing of contact Hit of the relay operates relay I83 which supplies current for the filaments and the plate current rectifier of the amplifiers 84, I85 from source It! over circuits similar to those described in connection with relay 39 of Fig. 2. Contact I86 of the switch completes a circuit from negative through priority relay E8! to positive through back contact I88 of priority relay I 89 of station I 23, and the operation of relay it? opens the circuit of relay I89 at contact E90 so that station l23 is now locked out. Relay l8? completes a circuit for relay I41 by closing contact I9! and the operation of relay I41 opens contact [192 to disconnect the local receiver Me and complete at contacts 5%, I94 the speech input circuit to the amplifier I85 previously prepared by the closing of contacts 535, 96 on the master switch i1 8.

As in the other syste 1. station E22 may obtain control of the receivers MS even though the system is already in use by station 623 by operating the cut-in switch lei addition to the master switch W8. A circuit is then complete from negative through switch Eel, contact 553 of switch H8, conductor ltd, relay conductor Zill to positive through contact @538 of relay I24. The operation of relay 2% completes a circuit for relay it? independently of relay it?) and the operation of relay it? gives control of the systern to station 522 as before.

Currents representing speech originating at transmitter 282 enter the amplifier its over conductors 2%, 2%. The output of this amplifier enters amplifier lt l over conductors 255, 26% and the output of the latter amplifier terminates at contacts set, 2538 of relay lii. This relay is operated whenever relay is operated except when its circuit is broken at contact I58 of relay Hit by the operation of an alarm signal switch in the system of Fig. 1. When. operated, relay II l connects contacts 2% to conductors till, it? so that receivers lid are energized by the currents from transmitter 2%.

Each of the stations 522 and 523 is also equipped with signal lamps see and The lamps 2% are lighted whenever relay is operated that is, whenever either station is using the system and lamps 2 l s are lighted whenever the receivers N3 of this system are in use by any one of the stations of theother system. In such a case conductor 95 in the circuit of relay E8 is connected to negative through contact H33 of relay I35 and the circuit for lamp 2M extends from conductor 95 to conductor 25 l, through the lamps to conductors 252 and 935 to positive through contact ill of relay 26.

In some cases it may be desirable to use the amplifiers of systems of this kind for other purposes when they are not in use. For example on naval ships they can be used in connection with sound picture equipment or with other sound reproducing apparatus to provide entertainment or instruction. In Fig. 2 the apparatus Bit which may be of any desired type is connected to the input of the amplifier it by relay tilt in its unoperated position by conductors 2l5, 2H5. The output conductors Hit, It] of amplifier it are connected to receivers Ell by conductors ZIB, 2I9 through contacts 2559, 22E of relay H8 in its unoperated position. For this purpose the amplifiers are energized by operating switch 222 to complete a circuit for relay 39 without operating relay 2%. If, however, while the amplifiers are being used in this manner it becomes necessary to use them for announcing or alarm signal purposes the operator proceeds to operate the system in the usual manner and the operation of relay 28 in any of the ways already described energizes relays 2M and lit to disconnect the input apparatus from the amplifiers and transfer their output to the group selecting relays ii to st so that the system may be used in the normal manner without delay.

While the invention has been described with reference to a particular embodiment, it will be understood that it may be modified in various ways within the scope of the following claims.

What is claimed is:

1. In a communication system the combination with at least two normally independently operative component parts each comprising a plurality of speech transmitting stations, an am- .plifier common to the stations, a receiver and means controllable from each of the stations for connecting the receiver to the amplifier, of selecting means at one of the transmitting stations in a first part of the system operable while the receiver of a second part of the system is connected to its amplifier for connecting said receiver to the amplifier of the first part of said system.

2. In a communication system the combination with at least two normally independently operative component parts each comprising a plurality of speech transmitting stations, an amplifier common to the stations, a receiver and receiver controlling means at each of the stations for connecting the receiver to the amplifier, of means associated with the amplifier in one of the parts for producing alarm signals, and means independent of the receiver controlling means of the speech transmitting stations for connecting the receivers of all parts of the system to the alarm signal means.

3. In a communication system the combination with at least two normally independently operative component parts each comprising a plurality of speech transmitting stations, an amplifier common to the stations, a receiver and means controllable from each of the stations for connecting the receiver to the amplifier, of means at one station in a first part of the system effective when another part of the system is not transmitting but while the receiver of the other part is connected to its amplifier for connecting the receiver of the other part to the amplifier of said first part of the system.

4. In a communication system, the combination with a plurality of transmitting stations, an amplifier common to the stations, a plurality of receivers associated with the amplifier and means at each of the stations for operatively connecting the stations with the amplifier, of means operated when one of the stations is so connected for disabling the other stations, and emergency means at the disabled stations operable while the stations are disabled for connecting them to the receivers.

5. In a communication system, the combination with a plurality of transmitting stations, a vacuum tube amplifier common to the stations, a plurality of receivers associated with the amplifier, and means. at each of the stations for operatively connecting the station with the amplifier, of means independent of the transmitting station for maintaining the tube filaments of the amplifier heated but below emission temperature, and means responsive to the operation of any of the stations for raising the filaments to emission temperature.

6. In a communication system, the combination with a plurality of speech transmitting stations, a plurality of signal transmitting stations, an amplifier common to the stations, a receiver, and means controlled at each of the stations for connecting the station and the receiver to the amplifier, of another transmitting station, another amplifier and another receiver, means for connecting said other station to its amplifier and receiver, means at each of the speech transmitting stations operable only when said other re ceiver is not connected to its amplifier and means at each of the signal transmitting stations operative at all times to connect said other receiver to the common amplifier.

'7. In a communicating system, the combination with a plurality of transmitting stations, an amplifier, a plurality of receivers, and means at each of the stations to connecting the station to the amplifier and the receivers, of sound reproducing apparatus and another receiver, normally open circuit connections between the apparatus and the amplifier and between the amplifier and said other receiver, and means for energizing the amplifier and closing said connections independently of the transmitting stations.

8. In a communicating station, the combina tion with a plurality of transmitting stations, an amplifier, a plurality of receivers, and means at each of the stations for connecting the station to the amplifier and the receivers, of sound reproducing apparatus and another receiver, circuit connections between the apparatus and the amplifier and between the amplifier and said other receiver, means for energizing the amplifier independently of the transmitting stations, and means responsive to the operaticn of one of the stations for automatically opening said circuit connections.

HERBERT C. CURL. 

